Brother T-8420B Instruction Manual page 41

10. TROUBLESHOOTING
Problem
4 Skipped stitches
while sewing
5 Skipped stitches at sewing
start
Thread unravelling
sewing start
35
occur Is the needle tip bent? Is the needle tip blunt?
If the needle tip is bent or broken, replace the needle.
Is the needle properly installed?
If it is incorrect, install the needle correctly.
Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
Is the presser foot pressure too weak?
Adjust the presser foot pressure.
Is the needle too thin?
Replace the needle with a needle that is one rank thicker.
Is the presser foot too high?
Adjust the height of the presser foot.
Is the thread take-up spring too weak?
Adjust the tension of the thread take-up spring.
Is the thread take-up amount too large?
Adjust the thread take-up amount.
2945M
Is the thread take-up spring tension too strong?
Reduce the tension of the thread take-up spring.
at Is the thread take-up spring operating range too large?
Raise the position of the stopper.
Is the thread take-up at its highest position at the sewing start?
Set the thread take-up to its highest position at the sewing start.
Is the length of the upper thread trailing from the needle hole too
short?
Pull about 50 mm of thread through the needle hole at the
sewing start.
Is the needle too wide?
Try using a needle with a count that is one lower than the
current needle.
If sewing light or medium-weight materials, is a presser foot with
slots on the underside or grooved feed dog being used?
Use a presser foot without slots.
Use a feed dog without grooves.
2946M
T-8420B, 8450B, 8720B, 8750B
Possible cause
Slot
Page
14
16-20
26
*
*
27
*
*
19
20
Grooves
2944M